What is one way to treat an adrenal insufficiency?

Steroids: If your adrenals have failed (called addison's disease) you need to be on adrenal replacement. This is usually hydrocortisone, maybe with Fludrocortisone too. Be careful, however. There are people treating "adrenal fatigue" with inadequate testing when in fact there is nothing wrong with the adrenals. One cannot rely on symptoms alone. An acth (cortrosyn) stim test is usually done for diagnosis.